1. Field of the Invention
The present invention relates to a vehicle head lamp and more particularly, a vehicle head lamp comprising a reflector for reflecting the light of a lamp and a lamp holder arranged at the back end of said reflector to hold the lamp, said reflector and lamp holder being made of synthetic resin.
2. Prior Art
The vehicle head lamp of this type generally comprises attaching a lens to the front end of the reflector whose inner surface is coated by a reflecting material and which is made of a synthetic resin, arranging the lamp holder, which is made of a synthetic resin, at the back end of said reflector, and attaching the lamp to the lamp holder. High luminosity lamps such as the incandescent lamp having a high watt filament housed in the glass envelope and the halogen lamp in which halogen cycle is caused in the glass envelope are recently used to enhance forward visibility in the vehicle.
When these high luminosity lamps are employed as the vehicle head lamp, however, the circumferential face of the lamp holder made of synthetic resin is subjected directly to the light emitted from the filament and thus deteriorated. Namely, the circumferential face of the lamp holder is subjected directly to high heat caused by the light being directly projected from the filament and when the head lamp is kept turned on for a long time, the synthetic resin of which the lamp holder is made deteriorate to generate gas, oil and fat, which are condensed on the reflecting material of the reflector, so that the reflecting material is whitened to lower its reflecting efficiency and thus its light distribution capacity as well as to lose its appearance.
This disadvantage because of deterioration will also be caused in a lamp wherein the filament is arranged near the circumferential face of the lamp holder, as seen in the high luminosity lamp.